The OpenWSN project is an open-source implementation of a fully standards-based protocol stack for capillary networks, rooted in the new IEEE802.15.4e Time Synchronized Channel Hopping standard. The novel IETF 6TiSCH protocols make IEEE802.15.4e TSCH perfectly interfaced with well-known Internet-of-Things IETF standards, such as 6LoWPAN, RPL and CoAP, thus enabling ultra-low power and highly reliable mesh networks which are fully integrated into the Internet. The resulting protocol stack will be cornerstone to the upcoming Machine-to-Machine revolution. OpenWSN is ported to numerous commercial available platforms from older 16-bit micro-controller to state-of-the-art 32-bit Cortex-M architectures. The tools developed around the low- power mesh networks include visualization and debugging software, a simulator to mimic OpenWSN networks on a PC, and the environment needed to connect those networks to the Internet. OpenWSN projects leads standardization efforts for ultra low power M2M networks while contributing with innovative protocols for scalable, distributed and energy efficient communications.